Process of treating rubber and products obtained thereby



Patented June 12, 1923.

UNITED STATES PATENT OFFICE.

SIDNEY I. CADWELL, OI LEONIA, NEW JERSEY, ASSIGNOB .TO THE NAUGA'IUOKCHEMICAL COMPANY, 01 NAUGATUCK, CONNECTICUT, A. CORPORATION 01 CON-NECTIGUT.

PROCESS OF TREATING RUBBER AND PRODUCTS OBTAINED THEBEBY.

No Drawing.

This invention relates to the vulcanization of rubber in the presence ofa new class of accelerators and vulcanizing agents and to the productsobtained thereby.

The primary object of the invention is to 'furnish a method for' thevulcanization of rubber in the presence of a new class of organiccompounds, withoutthe addition of sulphur as such. Another objectis tofurnish a new type of accelerating agents adapted for'use in thevulcanization of rubber containing a vulcanizing agent. A still furtherobject is to provide materials of the type described which shall becomparative- 1y inexpensive and at the same time very powerful. Anotherobject is to provide accelerators and curing agents which are capable offunctioning wellat temperatures below 286 F., as well as at temperaturesabove.

this point.

I The invention consists in vulcanizing rubber in the presence ofcompounds comprising the group -ss-, (t).

The compounds hereindescribed include derivatives of thiol sulphonicacid, dithiol sulphuric acid, dithiol sulphurous acid, acyl thiolsulphates, thio acyl thiol sulphonates, thiocarbamyl snlphonates, thiolsulphonates, sulphates and sulphites. These compounds all comprise thegroup in which 17. may be one or two. These cont 'Application filedlarch 17, 1927. Serial in. 176,285.

pounds maybe regarded as partially fulfillmg the requlrements of thegeneral formula RCSM, where M comprises S.

i db.

However, it is preferredto describe the com-- pounds as RS?R, 5).

(in which case B" may comprise alkyl or aryl and X a bivalent element orgroup). R m the above formula may be acyl, aryl or alkyl, and may beidentical with B.

One example of the invention is as follows:-100 parts of rubber, 10parts of zinc oxide, and 5 parts of dimethylthio carbamyl para toluenethiol sulphonate are mixed on a mill in the usual way. This stock Whenvulcanized in a mold for 1 hr. at 40 lbs. steam pressure is wellvulcanized. In this instance the compound functions as a vulcanizingagent, that is, causes vulcanization to take place without requiring theaddition of free sulphur or its equivalent. Stocks prepared in thismanner are characterized by excellent aging properties, and they do notovervulcanize readily.

As an example in which the thiolsulphonate is used as an accelerator,100 parts of rubber, 10 parts of zinc oxide, 3 parts of sul phur and0.15 parts of dimethyl thio carbamyl para toluene thiol sulphonate aremixed on the mills in the usual manner and the resulting batch cured for15 minutes at 40lbs. steam pressure. The resulting product is wellvulcanized. Equally good results may be obtained by vulcanizmg the abovestock in a mold for min. at 5 lbs. steam pressure. The thiol sulphonatemay he used in various proportions, and if desired may be used 111suficient amounts to function as thiol sulphonate may be prepared as,follows :-27 parts of dimethyl amine solution containing 33% by weightof dimethyl amine are mixed with 15.2 parts of carbon disulphide themixture being cooled externally. Afterwards 8 parts of sodium bydroxidedissolved in about 24 parts of water are added. The reaction mixturecontains the sodium salt of dimethyl dithiocarbamic acid.' To this arethen added in small portions during the course of hr., 38 parts offinely ground para toluene sulphonyl chloride, the mixture beingagitated and the temperature being maintained at approximately 25 C. Thestirring is continued for about 5 hrs., or until a dried sample of theproduct shows a melting point of 123 C. The reaction product is thenfiltered and washed with water until the washings are free fromchloride, after which the material is dried. The product may also be preared by dissolving the para toluene sulp onyl chloride in a waterimmiscible solvent such as benzol, toluol or solvent naphtha. Thissolution is stirred with an aqueous solution of any water soluble saltof the dithiocarbamate. Or the para toluene sulphonyl chloride and anyconvenient dithiocarbamate may be dissolved in a common solvent andallowed to react."

The diethyl compound may be prepared in the same general manner in hichthe dimethyl thiocarbamyl compound is made.

Bis(diethyl thiocarbamyl)dithiol sulphate may be prepared by allowingappropriate amounts of sulphuryl chloride and diethyldithiocarbamate toreact in a non-aqueous medium. The invention, however, is not limited toany specific method of preparation for the compounds herein described.

Derivatives of thiol sulphonic acid, dithiosulphuric acid or in generalcompounds of the formula RSfl?R may comprise various substitutions for Rand R. Among such compounds are the following:

Penta methylene thiocarbamyl para toluene thiol sulphonate, dimethylthiocarbamyl naphthalene thiol sulphonate, dimethyl thiocarbamyl benzolthiol sulphonate, benzothiazyl para toluene thiol sulphonate, bis(diethyl thiocarbamyl) dithiol sulphite, dimethyl thiocarbamylmeta-nitrobenzol thiol sulphonate, n-Butyl butyl thiol sulphonate,dimethyl thiocarbamyl 1-3 dimethyl benzol 4 thiol sulphonate, dimethylthiocarbamyl 2 nitrotoluene 4 thiol sulphonate, benzyl benzyl thiolsulphonate.

In the case of the dialkyl thiocarbamyl compounds, some of theacceleration is undoubtedly due to the rtion of the compound whichcorrespon s to the general formula R C S M,

but the strength of the accelerator (or of the curing agent, if it beused as such), is

30% to 40% reater than can be accounted for on the basis of the R ("I SM content. This excess in accelerating or vulcanizing strength is due tothe configuration. Where the compounds RSSR do not contain the groupR'CS it will be observed that such compounds are not as strong in theiraccelerating power. It has also been observed that'the heavier the alkylgroup in the dialkyl thiocarbamyl thiol sul onates the better do theaccelerators an vulcanizing agents resist burnin on the mixing mill. Itis also to be observe that dimethyl thiocarbam l derivatives are not aseflicacious as the diethyl and higher dialkyl derivatives in thepresence of litharge and the absence of zinc oxide. The higher dialkyl.derivatives are particularly va uable for use in rubber stockscontaining litharge. Accelerators agents of the type all).

are particularly .well suited for use in the presence of reclaimedrubbers, ofi-grade'rub-= ers and in highly compounded stocks. Manyaccelerators of this class function very well at steam pressures of 5,10' and lbs. The dialkyl thiocarbamyl derivatives are egrcellentaccelerators for use in the production of non-blooming air-cured stocks.

Many of the compounds, and particularly dialkyl thiocarbamyl derivativesof aryl thiol sulphonates have not previously been described in thechemical literature. The claims comprehend the use of these compounds asaccelerators oras vulcanizing agents, and are intended to include withintheir scope the use of these compounds to secure the valuablecharacteristics of and vulcanizing strength, elasticity, durability,resistance to deterioration whlch are sought in rubber products.

Having thus described my invention, what I claim and desire to protectby Letters Patent is:

1. Method of treating rubber which comprises vulcanizing'rubber in thepresence of an organic compound comprising the oup SS in which at leastone of the'su phur atoms has at least one atom of oxygen attachedthereto.

2. Method of treating rubber which comprises vulcanizing rubberin thepresence of an organic compound comprising the group SS in which atleast one sulphur atom has at least one atom of oxygen attached theretoby a double bond. I

3. Method of treating rubber which comprises vulcanizing rubber in thepresence of an organic compound comprisin the group SS in which onesulphur atom as at least one atom of oxygen attached thereto by. doublebond, and the other sulphur is attached to carbon.

4. Method of treating rubber which comprises vulcanizing rubb'erin thepresence of an organic compound comprisin the group SS in which onesulphur atom as at least one atom of oxygen attached thereto by-a doublebond, and the other sulphur is attached to carbon having a double bond.

5. Method of treating rubber which comprises vulcanizing rubber in thepresence of an organic compound of the type RSSR' in which both positiveand negative sulphur are present. 6. Method of treating rubber, whichcom- .au acyl thiolaci prises vulcanizing rubber in the presence of anorganic compound comprising the group 8. Method of treating rubber whichcom-- prises vulcanizing rubber in the presence of organic compoundscomprisFng the group- CSS MAB

9. Method of treating rubber which comprises vulcanizing rubber in thepresence of an organic compound of the type 10. Method of treatingrubber which comprises vulcanlzmg rubberv in' the resence of an organicderivative of thiolaci sol the 11. Method of treating rubber whichcomprises vulcanizing rubber in'thepresence of V p a thiolsulphonate ofthe type RS+S-R.

I 12. Method oftreating rubber which comprises vulcanizing rubber in thepresence of an organic thlolsulphonate of the type l 13. Method oftreating rubber which comprises vulcanizin rubber in the presence of ofthe type 14. Method of treating rubber which comprises vulcanizingrubber in the resence of a derivative of an organic thio acid containingthe grouping prises vulcanizing rubber in the presence of a derivativeof an aryl thiolsulphonate of 16. Method of treating rubber whichcomprises vulcanizin rubber in the presence of a toluene thiolsuphonate.

- 17. Method of treating rubber which comprises vulcanizing rubber inthe resence of an acyl derivative of an aryl t 'olsulphonate.

18. Method of treating rubber which comprises vulcanizing rubber in thepresence of a thioacyl derivative of an aryl thiolsul honate.

19. Method of treatingrubber which comprises vulcanizin rubber in thepresence of an acyl toluene thiolsulphonate.

20.' Method of treating rubber which comprises vulcam'zing rubber in thepresence of a thioacyl toluene thiolsulphonate.

21. Method of treating rubber which com prises vulcanizing rubber in thepresence of a carbamyl thiolsulphonate of the type 22. Method oftreating rubber which comprises vulcanizing rubber in the presence of acarbamyl aryl thiolsulphonate of the type 23. Method of treating rubberwhich comprises vulcanizing rubber in the presence of a carbamylderivative of a toluene thiolsulphonate.

24. Method of treating rubber which comprises vulcanizin rubber in theresence of an alkyl aryl thio sulphonate of t e type 25. Method oftreating rubber which comprises vulcanizin rubber in the presence of analkylaryl thio ulphonate of the type prises vulcanizing rubber in thepresence of a thio carbamyl thiolsulphonate of the type meg Egan 28.Method of treating rubber which coman alkyl thiocar amyl thiolsulphonate of the type RSSR.

30. Method of treating rubber which comprises vulcanizin rubber in thepresence of dimethyl thiocar amyl para toluene thiolsulphonate.

31. Vulcanized rubber derived from rubber vulcanized in the presence ofan organic compound comprising the 'roup SS in which at least one of thesulphur atoms has at least one atom of oxygen attached thereto.

32. Vulcanized rubber derived from rubber vulcanized in the presence ofan organic compound comprising the group SS in which at least onesulphur atom has at least one gtorg of oxygen attached thereto by adouble 33. Vulcanized rubber derived from rubber vulcanized in thepresence of an organic compound comprising the roup SS in which onesulphur atom has at east one atom of oxygen attached thereto by a doublebond,

and the other sulphur, is attached to carbon.

34. Vulcanized rubber derived from rubber vulcanized in the presence ofan organic compound comprising the group SS in which one sulphur atomhas at least one atom of oxygen attached thereto by a double bond, andthe other sulphur is attached to carbon having a double bond.

35. Vulcanized rubber derived from rubber vulcanized in the presence ofan organic compound of the type RSSR in which both positive and negativesulphur are present.

36. Vulcanized rubber derived from rubber vulcanized in the presence ofan organic compound comprising the group 37. Vulcanized rubber derivedfrom rubber vulcanized in the presence of organic compounds comprisingthe group CSS.

38. Vulcanized rubber derived from rubber vulcanized in the presence oforganic compounds comprising the group 39. Vulcanized rubber derivedfrom rubber vulcanized in the presence of an organic compound of thetype 40. Vulcanized rubber derived from rubber vulcanized in thepresence of an organic derivative of thiolacids of the type 41.Vulcanized rubber derived from rubber vulcanized in the presence of athiolsulphonate of the type 42. Vulcanized rubber derived from rubbervulcanized in the presence of an organic thiolsulphonate of the type RSSR.

43. Vulcanized rubber derived from rubber vulcanized in the presence ofan acyl thiolsulphonate of the type RSSR.

A 44. Vulcanizedrubber derived from rubber vulcanized in the presence ofa derivative of an organic thlol acid containing the grouping A5.Vulcanized'rubbe'r derived from rubber vulcanized in the presence of aderivative of an aryl thiolsulphonate of the type ber vulcanized in thepresence of a thioacyl derivative of an aryl thiolsulphonate'.

49. Vulcanized rubber derived from rub- 7 her vulcanized. in thepresence of an acyl toluene thiolsulphonate.

50. Vulcanized rubber derived from rubber vulcanized in the presence ofa thioacyl toluene thiolsulphonate.

51. Vulcanized rubber derived from rubber vulcanized in thepresence of acarbamyl thiolsulphonate of the type R'SSR.

52. Vulcanized rubber derived from rubber vulcanized in the presence ofa carbamyl aryl thiolsulphonate of the type 53. Vulcanized rubberderived from rubber vulcanized in the presence of a carbaniyl derivativeof a toluene thiolsulphonate.

54. Vulcanized rubber derived from rubber vulcanized in the presence ofan alkyl thiolsulphonate of the type R'SSR. (A)

55. Vulcanized rubber derived from rubber vulcanized in the presence ofan alkyl aryl thiolsulphonate of the type 56. Vulcanized rubber derivedfrom rubber vulcanized in the presence of an alkyl derivative of atoluene thiolsulphonate.

57. Vulcanized rubber derived from rubber vulcanized in the presence ofa thin carbamyl thiolsulphonte of the type 58. Vulcanized rubber derivedfrom rubber vulcanized in the presence of a thiccarbamyl derivative of atoluene thiolsul- .phonaie.

59. Vulcanized rubber derived from rub ber vulcanized in the resence ofan alkyl thiocarbamyl thiol sulp onate of the type 60. Vulcanized rubberderived from rubber vulcanized in the presence of dimethyl thiocarbarnylpara toluene thiolsulphonate. Signed at New York, count and State of NewYork, this 10th day-of arch, 1927.

SIDNEY M. CADWELL.

CERTIFICATE OF CORRECTION.

Patent No. 1,673,550. Granted June 12, 1928, to

SIDNEY M. CADWELL.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 4,line 43, claim 24, strike out the word "aryl"; page 5, line 108, claim57. for the misspelled word "thiolsulphonte" read "thiolsulphonate"; andthat the said Letters Patent should be read with these correctionstherein that the same may conform to the record of the case in thePatent Office.

Signed and sealed this 14th day of August, A. l). 1928.

. M. J. Moore, (Seal) Acting Commissioner of Patents.

